Flow-Injection Spectrophotometric Determination of Nitrite and Nitrate in Biological Samples

Higuchi, Keiro; Motomizu, Shoji

doi:10.2116/analsci.15.129

Cited by 45 publications

(33 citation statements)

References 14 publications

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“…Prior to analysis, samples were deproteinised using a modification of the technique described by Higuchi and Motomizo. 38 Plasma nitrate and nitrite concentration were determined using a Sievers nitric oxide analyser (Sievers NOA 280, Analytix Ltd, Durham, UK) using the methods described by Bateman et al 39 The between-batch coefficient of variation for nitrate was 13% (n=3) and for nitrite was 8% for a control plasma sample (n=11).…”

Section: Plasma Nitrate and Nitrite Analysismentioning

confidence: 99%

Effect of dietary nitrate on blood pressure, endothelial function, and insulin sensitivity in type 2 diabetes

Gilchrist

Winyard

Aizawa

et al. 2013

Free Radical Biology and Medicine

218

209

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Diets rich in green, leafy vegetables have been shown to lower BP and reduce the risk of cardiovascular disease. Green, leafy vegetables and beetroots are particularly rich in inorganic nitrate. Dietary nitrate supplementation, via sequential reduction to nitrite and NO, has previously been shown to lower BP and improve endothelial function in healthy humans.We sought to determine if supplementing dietary nitrate with beetroot juice, a rich source of nitrate, will lower BP, improve endothelial function and insulin sensitivity in individuals with type 2 diabetes (T2DM). Twenty-seven patients, age 67.2 +/-4.9 years, (18 male) were recruited for a double blind, randomised, placebo-controlled crossover trial. Participants were randomised to begin in either order a 2 week period of supplementation with 250 ml beetroot juice daily (active) or 250 ml nitratedepleted beetroot juice (placebo). At the conclusion of each intervention period 24 hour ambulatory blood pressure monitoring, tests of macro and microvascular endothelial function and a hyperinsulinaemic isoglycaemic clamp were performed. After two weeks administration of beetroot juice mean ambulatory systolic BP was unchanged: 134.6 ± 8.4 mmHg versus 135.1 ± 7.8 mmHg (mean ± SD) placebo vs. active -mean difference of -0.5 mmHg (placebo-active), p=0.737 (95% CI -3.9 to 2.8). There were no changes in macrovascular or microvascular endothelial function or insulin sensitivity. Supplementation of the diet with 7.5 mmoles of nitrate per day for 2 weeks caused an increase in plasma nitrite and nitrate concentration, but did not lower BP, improve endothelial function or insulin sensitivity in individuals with T2DM.3

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Section: Plasma Nitrate and Nitrite Analysismentioning

confidence: 99%

Effect of dietary nitrate on blood pressure, endothelial function, and insulin sensitivity in type 2 diabetes

Gilchrist

Winyard

Aizawa

et al. 2013

Free Radical Biology and Medicine

218

209

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“…It was important and necessary for maintaining the quantitative reduction that EDTA was involved in the carrier solution because the surface of Cd/Cu particles was washed out by formation of a Cd-EDTA complex and an active surface could appear any time. 20 The analytical signal was dependent on the changes of the length of the pathways to the detector. Lengths between 50 and 200 cm were tried, a decreasing in the analytical response being observed when longer pathways were used.…”

Section: System Optimizationmentioning

confidence: 99%

Sequential Injection Analysis-Based System for On-Line Monitoring of Nitrite and Nitrate in Wastewaters

2000

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The rapid growth of biotechnological research in the last years has emphasized the demand for simple and robust analytical techniques applicable to bioprocess monitoring.On-line determination of certain chemical species in bioprocesses is of significance with regard to controlling a process more efficiently, for reasons of economy, environmental quality and product quality. 1Automatic systems for on-line process control based on flow analyses were developed and used in the monitorization of chemical species in natural waters and industrial effluents. More robust systems with simple operation and a minimum of maintenance are therefore needed in order to advance the routine application to the industrial processes. The sequential injection analysis (SIA) comprising only a single propulsor system, single valve and a single channel, has been conceived and found to overcome the difficulties related to the conventional flow systems, such as, manual reconfiguration of the flow channel, high reagent consumption due to the continuous flow operation and frequent recalibration of the system. Routine application of the conventional flow systems for bioprocess monitoring is largely restricted to research laboratories, as the robustness and ease of operation are not sufficiently good for process control. 2-7Nitrite and nitrate are chemical species in waters that need monitoring, due to their known toxicity to animal and human metabolism, especially when children are concerned. Nitrate is related with methaemoglobinaemia (Blue Baby Syndrome) and there is a possible relation with stomach cancer and hypertension. [8][9][10][11][12] The nitrogen content, as nitrite and nitrate, of lakes, rivers and streams usually arises from the groundwater, sewerage effluent or drainage and leaching from agricultural land. 13 The last is the most significant input and nitrate levels have increased substantially because of the increased use of nitrogen-based fertilisers. [13][14][15] Several methods are available for the nitrite and nitrate determination in waters, [15][16][17] including direct ultraviolet spectrophotometry, derivatization with sulfosalicylic acid, use of a nitrate-selective electrode and reduction to nitrite followed by derivatization, e.g., with N-(1-naphtyl)ethylenediamine dihydrochloride (N1NED) and sulfanilamide.In this paper, the design of a fully automated and robust system based on SIA, allowing the simultaneous monitoring of nitrite and nitrate in wastewaters, is described. The nitrite determination is based on the Griess-Llosvay reaction: nitrite in the presence of sulfanilamide and N1NED produces, by diazotization and coupling reaction, a colored compound that can be spectrophotometrically detected at 543 nm. Nitrate is determined after reduction to nitrite in a copperized cadmium column. 18 The parameters that affect this determination were evaluated. The working characteristics of this system are rapid, sensitive and accurate, and applicable to the monitorization of nitrite and nitrate levels in wastewaters. Experime...

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“…[32][33][34] Flow injection analysis (FIA) in combination with one of the above detection methods have been widely used for the determination of nitrite. [14][15][16][17]35,36 Due to its inherent advantages, such as high sample throughput, improved precision and relatively simple equipment, FIA is widely used for water analysis in a rapid and efficient way.…”

Section: Introductionmentioning

confidence: 99%

A Simple Flow Injection Spectrophotometric Determination of Nitrite Based on Its Reaction with Thiourea

2005

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A simple flow injection spectrophotometric method for the determination of nitrite is described. Nitrite injected into the flow system reacts with thiourea in acidic medium and the generated thiocyanate ion reacts with Fe(III) in the reagent solution to produce a highly colored product. The influences of chemical and physical parameters including reagent concentrations, sample volume injected, flow rates of the carrier and reagent solutions, reaction coil length and reaction temperature, were studied and optimum values of these parameters were established. Under the optimum conditions, the calibration curve for nitrite was linear over the concentration range 0.36 -90 µg ml -1 without preconcentration and over the range 3.8 -500 ng ml -1 with a simple online preconcentration step using an anion exchange column. The corresponding detection limits were 0.36 µg ml -1 and 3.8 ng ml -1 , respectively. Up to 25 samples can be analyzed per hour, with an average relative standard deviation of ≤ 1.2%. Interferences by various foreign ions were studied and the method was applied to the determination of nitrite in water and spiked water samples.

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Flow-Injection Spectrophotometric Determination of Nitrite and Nitrate in Biological Samples

Cited by 45 publications

References 14 publications

Effect of dietary nitrate on blood pressure, endothelial function, and insulin sensitivity in type 2 diabetes

Effect of dietary nitrate on blood pressure, endothelial function, and insulin sensitivity in type 2 diabetes

Sequential Injection Analysis-Based System for On-Line Monitoring of Nitrite and Nitrate in Wastewaters

A Simple Flow Injection Spectrophotometric Determination of Nitrite Based on Its Reaction with Thiourea

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